1. Field of the Invention
The present invention relates to a method and an apparatus for die bonding in a process for manufacturing semiconductor devices.
2. Description of the Related Art
FIG. 1 shows a conventional die bonding apparatus disclosed in Japanese Patent Laid-Open No. 60-183733. In the drawing, a wafer 1 is held on a wafer fixing member 10. This wafer 1 is divided into a multiplicity of semiconductor chips 1a, and these semiconductor chips 1a are spaced apart with intervals provided therebetween. A pickup head 2 for lifting i.e., by vacuum, each of the semiconductor chips 1a and for transferring the same onto a lead frame 8 is disposed above the wafer 1. A pickup head controlling means 5 is connected to this pickup head 2. An ITV (industrial television) camera 3 for viewing the semiconductor chip 1a is disposed above the pickup head 2, and a pattern recognition processing means 4 is connected to the ITV camera 3. The wafer fixing member 10 is provided on an X-Y moving stage 6, to which an X-Y moving stage controlling means 7 is connected. A controller 9 is connected to the pattern recognition processing means 4, the pickup head controlling means 5, and the X-Y moving stage controlling means 7, to control these controlling means.
A description will now be given of the operation of this conventional die bonding apparatus. One semiconductor chip 1a on the wafer fixing member 10 is detected by the ITV camera 3, and a signal produced by this ITV camera 3 is processed by the pattern recognition processing means 4 to determine whether or not the semiconductor chip 1a is free of defects. If the semiconductor chip 1a is nondefective, the controller 9 supplies commands to the pickup head controlling means 5 and the X-Y moving stage controlling means 7 to initiate operations. As a result, subsequent operations are carried out consecutively, including the positioning of the nondefective semiconductor chips 1a by the X-Y moving stage 6, the transfer of the nondefective semiconductor chips 1a onto the lead frame 8 and the bonding of them to die pads (not shown) of the lead frame 8 by the pickup head 2.
However, as shown in FIG. 1, although the lead frame 8 is located in the vicinity of the X-Y moving stage 6, the lead frame 8 and the X-Y moving stage 6 are both disposed in horizontally spaced positions. Accordingly, in order to transfer the semiconductor chip 1a, it has been necessary to raise the pickup head 2 vertically from the wafer fixing member 10, then move the pickup head 2 horizontally, and then lower the same to the die pad of the lead frame 8. For this reason, there have been drawbacks in that a long period of time is required in transferring the semiconductor chips 1a with a resultant decline in the production yield of semiconductor devices, and the die bonding apparatus tends to be large in size since the distance over which the semiconductor chip 1a is transferred is relatively long.